Benitez has been in talks with the European champions since his six-year spell as Liverpool manager was ended by mutual consent last week.
"We have agreed the final details, which were not important things. Tomorrow we shall present Rafa Benitez," Moratti said last night.
The Inter president went on to tell reporters that "all that is needed now is a countersignature".
Moratti added that negotiations with Benitez had not taken place in person but revealed the Spaniard would fly to Milan in time for today's presentation.
"I think Benitez is not in Italy and will arrive for the presentation," he said. "We will tell you when he will be presented."
Moratti revealed on Monday that a deal with the 50-year-old had been "more or less done" and had been confident the details would be finalised yesterday. Reports in Italy had suggested Benitez would sign a three-year deal worth 5million per season, but Moratti denied those claims as "off track" in terms of "duration and the amount".
Benitez may wish to take his Anfield assistant Mauricio Pellegrino, goalkeeping coach Xavi Valero and fitness coach Paco de Miguel with him to the San Siro, with Italian Amedeo Carboni – who played under Benitez as a midfielder at Valencia – also touted as a possible backroom addition.
Benitez still had four years to run on his Liverpool contract but left after the Reds could only manage seventh place in the Premier League last season. Liverpool also suffered early exits in the Champions League, FA Cup and Carling Cup. Benitez had previously been linked with Real Madrid, but they filled their managerial vacancy by wooing Jose Mourinho from Inter after he took them to the treble last season.
Fernando Torres marked his return from injury with a goal as Spain routed Poland 6-0 in its last World Cup warm-up match in Murcia last night, but the European champions were left with doubts over Andres Iniesta after the playmaker came off early.
Iniesta provided the pass for David Villa's opener before starting the move which led to David Silva's 14th-minute goal. He came off in the 39th with an apparent leg problem.
Xabi Alonso scored in the 51st before setting up Cesc Fabregas seven minutes later in the Arsenal midfielder's second game back from a fractured leg.
Torres guided Pedro Rodriguez's pass home in the 76th before Pedro scored in the 81st.
Spain, who have won their last 11 games, go into the tournament in South Africa as favourites to win their first world title.